Hmmm... Several candidates, but I think that the worst offender was someone I knew in HS.
1.
He wore his hair down well past his shoulders, but never even decided to get a bang trim. This eccentuated the fact that he was unspeakably ugly, and one VERY nice girl I knew once told me that his smile made her want to punch him out, and another exceptionally kind person called him "dirty."
2. He was suspended for making death threats against another student.
3. The track team nicknamed him "Shaggy" because of his long hair, yet he STILL refused to get it cut.
4. He once asked a girl out to Junior Prom or Senior Ball (I can't remember which), but the total elapsed time spent on the phone before he was rejected was less than ONE MINUTE.
5. While a senior in HS, he spent his time on a field trip playing "tag."
6. The kid spent all of his money obsessing over the latest Japanese/Chinese animation products and art design, and even occasionally pretended to be Japanese because he thought it was cooler than Chinese. Note that his last name was "Chen."
7. He was rejected from every major university that he applied to (his parents wanted him to go to Berkeley), and ended up going into Riverside.
8. Sometimes cleaned his nails in the middle of class periods using scissors.
9. He once attempted to claim that he was better at talking to girls than I was. Unfortunately for him, there were numerous girls in the room at the time who proceeded to tell him off. Sometimes with hilarious statements.
10. Although I occasionally felt sorry for him due to the high expectations heaped on him by his parents, most of the time I was repulsed by the fact that he rarely bathed and occasionally wore the same clothes to school for three to five days at a time. This sentiment was also echoed by many of my friends, of both genders, and was not lessened by the fact that he ran on the track team.
11. Once sat in history class, tasting his hair, and eventually came to the conclusion that his "hair tastes like pasta."